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Re: Slow planes was: Battle blimps

From: Allan Goodall <agoodall@a...>
Date: Fri, 19 Apr 2002 09:18:44 -0500
Subject: Re: Slow planes was: Battle blimps

On Fri, 19 Apr 2002 09:32:25 +1000, Beth.Fulton@csiro.au wrote:

>So you could (may be) imagine a situation where they sit WAY up. 

I'm not sure what the ceiling is on a blimp/zepplin.

I know that there _was_ a ceiling. One of the problems zeppelins had was
that
once they achieved a certain height they had to vent gas. The higher you
go,
the less pressure on the gas. The gas would expand. If you let it expand
too
much, the gas containment would rupture. So, they would vent gas.
Zeppelins
would sometimes rise due to thermals, or other conditions (sunlight
could, I
believe, heat up the gas and give the ship more lift). So, they then had
to
vent gas to stop going too high and rupturing. Of course this meant that
when
the conditions changed the ship would start to sink. They could pump in
more
gas from containers, or they could dump ballast. Eventually they ran out
of
gas and ballast and had to go home.

I suppose a very high tech zeppelin could rise very high, but I'm not
sure
what the operational limits are. 

Allan Goodall		       agoodall@hyperbear.com
http://www.hyperbear.com

"At long last, the earthy soil of the typical, 
unimaginable mortician was revealed!" 


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